Refrigerator doors are known in the art. For example, see U.S. Patent Document Nos. 2010/0209730 and 2012/0090246, the disclosures of which are hereby incorporated herein by reference.
Refrigerated merchandisers often display food products in a product display area. In order to reduce the amount of heat entering the refrigerated area, they often include glass doors that also provide visibility and accessibility to consumers. Because glass is a poor thermal insulator, such doors often include two or three separates panes of glass with one or two spaces between them to increase the thermal insulation of the door. Thus, current refrigerator doors may often be thought of as including one or two insulating glass units (IGUs).
Because of the need for increased energy efficiency of refrigerated display systems, increased thermal insulation of the IGU can be achieved by using low-emissivity (low-E) coatings on one or more of the inner surfaces of the IGU. In one application known as “retrofit,” open refrigerated displays in food stores (i.e., displays with no glass doors) can be retrofitted with glass doors of the single of double pane type in order to minimize thermal loss from the refrigerated area thereby increasing the energy efficiency of the system. An undesired consequence of providing glass doors in refrigerated display areas is the loss or reduction of impulse sales, because customers now have a physical barrier between the merchandise and themselves. In this respect, the increase in visible reflectance which typically occurs when glass doors are provided in a refrigerated display area increases distortions and makes the merchandise (e.g., food) behind the doors difficult for shoppers to clearly see—this leads to reduced impulse sales.
Unfortunately, however, one undesirable consequence of this approach involves the rapid loss of light transmission through the IGU as more glass panes and more low-E coatings are incorporated. This, in turn, results in diminished marketing value of the door.
Thus, it will be appreciated that there is a need in the art for increasing the energy efficiency of the IGUs that make up refrigerator doors while at the same time increasing the visible light transmission through it, and methods of making the same.
U.S. Patent Document No. 2012/0090246 discloses a three pane refrigerator door including AR coatings and, low-E coatings. However, discrete silver based low-E coatings like the ones in the '246 patent document use up an entire available surface of a glass substrate that could otherwise be used for an AR coating. Therefore, in certain example embodiments of this invention, it is desirable to provide a solution that, at least in some instances, combines an infrared (IR) reflecting low-E layer with an AR layer structure in a single coating.
In certain example embodiments of this invention, refrigerator doors/windows (which includes freezer doors/windows) are provided for use in display areas where refrigerated merchandise (e.g., frozen or chilled food) is displayed. It is desired to increase energy efficiency of the doors and thus of the refrigerated display system, while at the same time reducing visible reflectance from the doors to make it easier for customers to see merchandise which is being displayed behind the transparent doors. Refrigerator doors (including windows) according to certain example embodiments of this invention include one or more AR coatings, some of which may include a transparent conductive layer (e.g., ITO) that reflects IR so as to also function as a low-E coating. Improvements can be achieved by combining, in one coating, AR functionality and low-E functionality. It is also possible that low-iron type glass may be used in the doors in certain example instances, which renders the doors even more transparent to visible light.
In certain example embodiments of this invention, there is provided a transparent refrigerator door/window comprising: at least first and second glass substrates; a combination anti-reflective and low-E coating on an interior surface of the first glass substrate, so that the coating is not exposed to a refrigerated environment adjacent the refrigerator door/window or a room environment adjacent the refrigerator door/window; wherein the coating comprises a transparent conductive layer comprising or consisting essentially of indium-tin-oxide (ITO) that is located between at least a dielectric layer comprising or consisting essentially of silicon oxynitride and a dielectric layer comprising or consisting essentially of silicon oxide, and wherein the dielectric layer comprising silicon oxynitride is located between at least the first glass substrate and the transparent conductive layer comprising ITO.
In certain example embodiments of this invention, there is provided a transparent refrigerator door/window comprising: at least first and second glass substrates; a combination anti-reflective and low-E coating on an interior surface of the first glass substrate, so that the coating is not exposed to a refrigerated environment adjacent the refrigerator door/window or a room environment adjacent the refrigerator door/window; wherein the coating comprises an IR reflecting transparent conductive oxide layer having a refractive index of from 1.8 to 2.0 that is located between at least a first dielectric layer having a refractive index of from 1.65 to 1.85 and a second dielectric layer having a refractive index of from 1.5 to 1.7, and wherein the first dielectric layer is located between at least the first glass substrate and the transparent conductive oxide layer; and wherein the transparent conductive oxide layer has a refractive index (n) at least 0.1 higher than respective refractive indices of the first and second dielectric layers.
In certain example embodiments of this invention, there is provided a transparent refrigerator door/window comprising: a glass substrate; first and second coatings on opposite major surfaces of the glass substrate; wherein the first coating is an anti-reflection coating or a low-E coating; and wherein the second coating is a combination anti-reflective and low-E coating that comprises a transparent conductive layer comprising ITO that is located between at least a dielectric layer comprising silicon oxynitride and a dielectric layer comprising silicon oxide, and wherein the dielectric layer comprising silicon oxynitride is located between at least the glass substrate and the transparent conductive layer comprising ITO.